How to spin in circle instances of metaballs?
My approach is to use metaballs as dupliverts

This subprogram (bluish) creates user defined amount of pointclouds.
To loop animation I used a couple of identical vector Wiggle nodes, but one with subtracted evaluation to make a smooth transition back to initial position.
Another subprogram (green) is mixing every point between pointclouds from both Wiggle nodes.

This part of a tree controls central point rotation (same trick with looping of two Wiggle nodes was used previously) and location (for location I used Empty).
First node from left named as Animation Duration controls animation length before looping.
Distribute Matrices node produces locations for pointclouds. Right now it replicates along the circle, but could be any mesh if needed.
Two Animate nodes are mixing start/end positions and use sinusoidal interpolation to give smoother looping.

Parent Metaball to freshly created pointcloud mesh - Target and enable duplivert instancing in mesh's object properties. To hide original metaball use shader mask: